The Measurements And Match Of Power Ultrasonic Transducers

This paper describes a system of ultrasonic transducer lithotripter and explores the main methods of its measurement and matching method.Relying on a strong platform of mathematics,Mathcad,it has a very good interface and interactive programming environment.Hope that through the ultrasonic transducer system modeling and analysis of the circuit,a testing ultrasonic lithotripsy machine can be designed.Its working frequency is in the 23 KHz and power is around 100 W.Working parts are composed of the piezoelectric ceramic transducer,horn and working under.It can crush kidney stone which is less than 3 millimeters and gettering the debris through the vacuum suction.The ultrasonic lithotripter includes: power supply,drive circuit,control circuit matching circuit and so on.In order to increase the mill's performance and practicality,a great deal of testing and improvements were made to achieve optimal results.After multiple measurement and study for ultrasonic lithotripsy system,the subject has constructed the accurate circuit models for ultrasonic transducer system,and obtains a reliable circuit parameters.After the exploration of the circuit model,a practical measurement for ultrasonic transducer system has been mastered and a set of effective matching method has been proposed.At last the research for the stable state response of the electric circuit was made.It confirmed feasibility and the reliability of electric circuit.This subject has successfully made an experimental ultrasonic lithotripsy machine.This paper calculates the matching inductance by the traditional method,analyzes matching circuit,and establishes the current and voltage formula for the circuit after matching the ultrasonic transducer.It results that it is easy to get working point of the large current on both side of resonance point through matching in the traditional method.Generally while the working state of the ultrasonic transducer is nearby the resonance point,the current of the ultrasonic transducer would be the biggest.So normally the resonance point is tracing by following the current.Hence in the traditional matching method,this way of tracing resonance point is easy to result the ultrasonic transducer not working at the resonance point.This would generate a lot of reactive power,and make the transducer heating seriously which is the same as the feedback from Guangzhou Medical College.The matching power of ultrasonic transducer produced by a lot of manufacturers,which output power is great,but the output power of ultrasonic transducer is not very big and the transducer heating very serious.After analyzing the traditional matching method,this paper presents a solution of firstly fixing the resonant frequency,and then reversely obtaining the matching inductance which is stably working on the resonant frequency.After deeply theoretical analysis and multiple experimental design,this paper finally designs an ultrasonic lithotripter whose working power is around 100 W and working frequency between 22.27 KHz to 22.45 KHz based on this kind of ultrasonic transducer.This ultrasonic lithotripter machine is very good to overcome the problem of the heating of ultrasonic transducer and the short life.